This application requests support to continue an international collaborative study on hypertension in populations of West African origin. During the first phase of this project 12,000 adults between the ages of 25 and 74 will be sampled from 7 communities: West Africa (Nigeria, urban & rural; Cameroon, urban & rural), the West Indies (St. Lucia, Barbados) and Maywood (lllinois). The screening examination provides information on blood pressure (BP), height, weight, waist/hip ratio, alcohol use, education/occupation, sodium/potassium excretion and social stress. These data will provide estimates of hypertension prevalence in each geographic region and the contribution of the known risk factor to higher rates among US blacks. In the first phase considerable effort has been directed toward establishing a strong research infrastructure in each of the sites and demonstrating the feasibility of cross-national BP comparisons. In the second phase we propose to continue and extend this research in three areas: 1) Population studies on risk factors. At the time of the original application it was not clear that adequate procedures were available to allow standardization of mean BP across sites, especially since differences between some sites might be as little as 2 mmHg. Experience to date suggests it will be feasible to collect definitive data on this question, as proposed in this application. In-depth studies will be carried out at one of the African sites to investigate the earliest stages of hypertension risk for a population. Investigators in Jamaica and the United Kingdom have joined the collaborative group and will examine the effect of migration from the Caribbean to the UK. 2) Prospective study of blood pressure and mortality. It is well known that hypertension accounts for much of the excess mortality among US blacks. It is less well recognized, however, that death rates among blacks in the US are higher than reported in the Caribbean or Africa. Hypertension is likely to account for that differential. A follow-up study in each region is proposed to estimate the relative and attributable risk from hypertension. 3) Heredity/Genetics. The populations in this study share a common ancestral origin in West Africa. We propose to undertake family studies to determine the heritability of blood pressure/hypertension within and between sites. In addition, pilot studies on genetic distance and candidate genes for hypertension will be conducted. The increased risk of hypertension in US blacks remains a major unsolved public health problem. Comparisons between macro-population groups in the US suffer from confounding by social factors and genetic admixture. The international comparative design provides a unique opportunity to study the evolution of hypertension among populations with a common genetic background currently living in widely varied social conditions. A well- organized network of investigators currently exists in the societies of the black diaspora and provides for the first time an opportunity to conduct cross-national research on this question.